CHRONIC BRONCHITIS:

Chronic bronchitis causes inflammation and mucus production in the bronchi, which are airways in the lungs. The inflammation and mucus cause a productive cough and make it difficult for a person to breathe.

Chronic bronchitis develops over time. In most cases, it is the result of long-term or frequent exposure to irritants or small particles that cause damage to the lungs.

Several potential risk factors for chronic bronchitis include:

smoking; females who smoke may be at more risk than males who smoke
childhood respiratory disease
family history of lung disease
exposure to pollutants
asthma
allergies
gastroesophageal reflux disease (GERD)